x86/xen: resume timer irqs early

[linux/fpc-iii.git] / drivers / usb / core / driver.c

/*
 * drivers/usb/driver.c - most of the driver model stuff for usb
 *
 * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
 *
 * based on drivers/usb/usb.c which had the following copyrights:
 *      (C) Copyright Linus Torvalds 1999
 *      (C) Copyright Johannes Erdfelt 1999-2001
 *      (C) Copyright Andreas Gal 1999
 *      (C) Copyright Gregory P. Smith 1999
 *      (C) Copyright Deti Fliegl 1999 (new USB architecture)
 *      (C) Copyright Randy Dunlap 2000
 *      (C) Copyright David Brownell 2000-2004
 *      (C) Copyright Yggdrasil Computing, Inc. 2000
 *              (usb_device_id matching changes by Adam J. Richter)
 *      (C) Copyright Greg Kroah-Hartman 2002-2003
 *
 * NOTE! This is not actually a driver at all, rather this is
 * just a collection of helper routines that implement the
 * matching, probing, releasing, suspending and resuming for
 * real drivers.
 *
 */

#include <linux/device.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/usb.h>
#include <linux/usb/quirks.h>
#include <linux/usb/hcd.h>

#include "usb.h"


/*
 * Adds a new dynamic USBdevice ID to this driver,
 * and cause the driver to probe for all devices again.
 */
ssize_t usb_store_new_id(struct usb_dynids *dynids,
                         struct device_driver *driver,
                         const char *buf, size_t count)
{
        struct usb_dynid *dynid;
        u32 idVendor = 0;
        u32 idProduct = 0;
        unsigned int bInterfaceClass = 0;
        int fields = 0;
        int retval = 0;

        fields = sscanf(buf, "%x %x %x", &idVendor, &idProduct,
                                        &bInterfaceClass);
        if (fields < 2)
                return -EINVAL;

        dynid = kzalloc(sizeof(*dynid), GFP_KERNEL);
        if (!dynid)
                return -ENOMEM;

        INIT_LIST_HEAD(&dynid->node);
        dynid->id.idVendor = idVendor;
        dynid->id.idProduct = idProduct;
        dynid->id.match_flags = USB_DEVICE_ID_MATCH_DEVICE;
        if (fields == 3) {
                dynid->id.bInterfaceClass = (u8)bInterfaceClass;
                dynid->id.match_flags |= USB_DEVICE_ID_MATCH_INT_CLASS;
        }

        spin_lock(&dynids->lock);
        list_add_tail(&dynid->node, &dynids->list);
        spin_unlock(&dynids->lock);

        retval = driver_attach(driver);

        if (retval)
                return retval;
        return count;
}
EXPORT_SYMBOL_GPL(usb_store_new_id);

ssize_t usb_show_dynids(struct usb_dynids *dynids, char *buf)
{
        struct usb_dynid *dynid;
        size_t count = 0;

        list_for_each_entry(dynid, &dynids->list, node)
                if (dynid->id.bInterfaceClass != 0)
                        count += scnprintf(&buf[count], PAGE_SIZE - count, "%04x %04x %02x\n",
                                           dynid->id.idVendor, dynid->id.idProduct,
                                           dynid->id.bInterfaceClass);
                else
                        count += scnprintf(&buf[count], PAGE_SIZE - count, "%04x %04x\n",
                                           dynid->id.idVendor, dynid->id.idProduct);
        return count;
}
EXPORT_SYMBOL_GPL(usb_show_dynids);

static ssize_t new_id_show(struct device_driver *driver, char *buf)
{
        struct usb_driver *usb_drv = to_usb_driver(driver);

        return usb_show_dynids(&usb_drv->dynids, buf);
}

static ssize_t new_id_store(struct device_driver *driver,
                            const char *buf, size_t count)
{
        struct usb_driver *usb_drv = to_usb_driver(driver);

        return usb_store_new_id(&usb_drv->dynids, driver, buf, count);
}
static DRIVER_ATTR_RW(new_id);

/*
 * Remove a USB device ID from this driver
 */
static ssize_t remove_id_store(struct device_driver *driver, const char *buf,
                               size_t count)
{
        struct usb_dynid *dynid, *n;
        struct usb_driver *usb_driver = to_usb_driver(driver);
        u32 idVendor;
        u32 idProduct;
        int fields;

        fields = sscanf(buf, "%x %x", &idVendor, &idProduct);
        if (fields < 2)
                return -EINVAL;

        spin_lock(&usb_driver->dynids.lock);
        list_for_each_entry_safe(dynid, n, &usb_driver->dynids.list, node) {
                struct usb_device_id *id = &dynid->id;
                if ((id->idVendor == idVendor) &&
                    (id->idProduct == idProduct)) {
                        list_del(&dynid->node);
                        kfree(dynid);
                        break;
                }
        }
        spin_unlock(&usb_driver->dynids.lock);
        return count;
}

static ssize_t remove_id_show(struct device_driver *driver, char *buf)
{
        return new_id_show(driver, buf);
}
static DRIVER_ATTR_RW(remove_id);

static int usb_create_newid_files(struct usb_driver *usb_drv)
{
        int error = 0;

        if (usb_drv->no_dynamic_id)
                goto exit;

        if (usb_drv->probe != NULL) {
                error = driver_create_file(&usb_drv->drvwrap.driver,
                                           &driver_attr_new_id);
                if (error == 0) {
                        error = driver_create_file(&usb_drv->drvwrap.driver,
                                        &driver_attr_remove_id);
                        if (error)
                                driver_remove_file(&usb_drv->drvwrap.driver,
                                                &driver_attr_new_id);
                }
        }
exit:
        return error;
}

static void usb_remove_newid_files(struct usb_driver *usb_drv)
{
        if (usb_drv->no_dynamic_id)
                return;

        if (usb_drv->probe != NULL) {
                driver_remove_file(&usb_drv->drvwrap.driver,
                                &driver_attr_remove_id);
                driver_remove_file(&usb_drv->drvwrap.driver,
                                   &driver_attr_new_id);
        }
}

static void usb_free_dynids(struct usb_driver *usb_drv)
{
        struct usb_dynid *dynid, *n;

        spin_lock(&usb_drv->dynids.lock);
        list_for_each_entry_safe(dynid, n, &usb_drv->dynids.list, node) {
                list_del(&dynid->node);
                kfree(dynid);
        }
        spin_unlock(&usb_drv->dynids.lock);
}

static const struct usb_device_id *usb_match_dynamic_id(struct usb_interface *intf,
                                                        struct usb_driver *drv)
{
        struct usb_dynid *dynid;

        spin_lock(&drv->dynids.lock);
        list_for_each_entry(dynid, &drv->dynids.list, node) {
                if (usb_match_one_id(intf, &dynid->id)) {
                        spin_unlock(&drv->dynids.lock);
                        return &dynid->id;
                }
        }
        spin_unlock(&drv->dynids.lock);
        return NULL;
}


/* called from driver core with dev locked */
static int usb_probe_device(struct device *dev)
{
        struct usb_device_driver *udriver = to_usb_device_driver(dev->driver);
        struct usb_device *udev = to_usb_device(dev);
        int error = 0;

        dev_dbg(dev, "%s\n", __func__);

        /* TODO: Add real matching code */

        /* The device should always appear to be in use
         * unless the driver supports autosuspend.
         */
        if (!udriver->supports_autosuspend)
                error = usb_autoresume_device(udev);

        if (!error)
                error = udriver->probe(udev);
        return error;
}

/* called from driver core with dev locked */
static int usb_unbind_device(struct device *dev)
{
        struct usb_device *udev = to_usb_device(dev);
        struct usb_device_driver *udriver = to_usb_device_driver(dev->driver);

        udriver->disconnect(udev);
        if (!udriver->supports_autosuspend)
                usb_autosuspend_device(udev);
        return 0;
}

/*
 * Cancel any pending scheduled resets
 *
 * [see usb_queue_reset_device()]
 *
 * Called after unconfiguring / when releasing interfaces. See
 * comments in __usb_queue_reset_device() regarding
 * udev->reset_running.
 */
static void usb_cancel_queued_reset(struct usb_interface *iface)
{
        if (iface->reset_running == 0)
                cancel_work_sync(&iface->reset_ws);
}

/* called from driver core with dev locked */
static int usb_probe_interface(struct device *dev)
{
        struct usb_driver *driver = to_usb_driver(dev->driver);
        struct usb_interface *intf = to_usb_interface(dev);
        struct usb_device *udev = interface_to_usbdev(intf);
        const struct usb_device_id *id;
        int error = -ENODEV;
        int lpm_disable_error;

        dev_dbg(dev, "%s\n", __func__);

        intf->needs_binding = 0;

        if (usb_device_is_owned(udev))
                return error;

        if (udev->authorized == 0) {
                dev_err(&intf->dev, "Device is not authorized for usage\n");
                return error;
        }

        id = usb_match_id(intf, driver->id_table);
        if (!id)
                id = usb_match_dynamic_id(intf, driver);
        if (!id)
                return error;

        dev_dbg(dev, "%s - got id\n", __func__);

        error = usb_autoresume_device(udev);
        if (error)
                return error;

        intf->condition = USB_INTERFACE_BINDING;

        /* Probed interfaces are initially active.  They are
         * runtime-PM-enabled only if the driver has autosuspend support.
         * They are sensitive to their children's power states.
         */
        pm_runtime_set_active(dev);
        pm_suspend_ignore_children(dev, false);
        if (driver->supports_autosuspend)
                pm_runtime_enable(dev);

        /* If the new driver doesn't allow hub-initiated LPM, and we can't
         * disable hub-initiated LPM, then fail the probe.
         *
         * Otherwise, leaving LPM enabled should be harmless, because the
         * endpoint intervals should remain the same, and the U1/U2 timeouts
         * should remain the same.
         *
         * If we need to install alt setting 0 before probe, or another alt
         * setting during probe, that should also be fine.  usb_set_interface()
         * will attempt to disable LPM, and fail if it can't disable it.
         */
        lpm_disable_error = usb_unlocked_disable_lpm(udev);
        if (lpm_disable_error && driver->disable_hub_initiated_lpm) {
                dev_err(&intf->dev, "%s Failed to disable LPM for driver %s\n.",
                                __func__, driver->name);
                error = lpm_disable_error;
                goto err;
        }

        /* Carry out a deferred switch to altsetting 0 */
        if (intf->needs_altsetting0) {
                error = usb_set_interface(udev, intf->altsetting[0].
                                desc.bInterfaceNumber, 0);
                if (error < 0)
                        goto err;
                intf->needs_altsetting0 = 0;
        }

        error = driver->probe(intf, id);
        if (error)
                goto err;

        intf->condition = USB_INTERFACE_BOUND;

        /* If the LPM disable succeeded, balance the ref counts. */
        if (!lpm_disable_error)
                usb_unlocked_enable_lpm(udev);

        usb_autosuspend_device(udev);
        return error;

 err:
        usb_set_intfdata(intf, NULL);
        intf->needs_remote_wakeup = 0;
        intf->condition = USB_INTERFACE_UNBOUND;
        usb_cancel_queued_reset(intf);

        /* If the LPM disable succeeded, balance the ref counts. */
        if (!lpm_disable_error)
                usb_unlocked_enable_lpm(udev);

        /* Unbound interfaces are always runtime-PM-disabled and -suspended */
        if (driver->supports_autosuspend)
                pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);

        usb_autosuspend_device(udev);
        return error;
}

/* called from driver core with dev locked */
static int usb_unbind_interface(struct device *dev)
{
        struct usb_driver *driver = to_usb_driver(dev->driver);
        struct usb_interface *intf = to_usb_interface(dev);
        struct usb_device *udev;
        int error, r, lpm_disable_error;

        intf->condition = USB_INTERFACE_UNBINDING;

        /* Autoresume for set_interface call below */
        udev = interface_to_usbdev(intf);
        error = usb_autoresume_device(udev);

        /* Hub-initiated LPM policy may change, so attempt to disable LPM until
         * the driver is unbound.  If LPM isn't disabled, that's fine because it
         * wouldn't be enabled unless all the bound interfaces supported
         * hub-initiated LPM.
         */
        lpm_disable_error = usb_unlocked_disable_lpm(udev);

        /* Terminate all URBs for this interface unless the driver
         * supports "soft" unbinding.
         */
        if (!driver->soft_unbind)
                usb_disable_interface(udev, intf, false);

        driver->disconnect(intf);
        usb_cancel_queued_reset(intf);

        /* Reset other interface state.
         * We cannot do a Set-Interface if the device is suspended or
         * if it is prepared for a system sleep (since installing a new
         * altsetting means creating new endpoint device entries).
         * When either of these happens, defer the Set-Interface.
         */
        if (intf->cur_altsetting->desc.bAlternateSetting == 0) {
                /* Already in altsetting 0 so skip Set-Interface.
                 * Just re-enable it without affecting the endpoint toggles.
                 */
                usb_enable_interface(udev, intf, false);
        } else if (!error && !intf->dev.power.is_prepared) {
                r = usb_set_interface(udev, intf->altsetting[0].
                                desc.bInterfaceNumber, 0);
                if (r < 0)
                        intf->needs_altsetting0 = 1;
        } else {
                intf->needs_altsetting0 = 1;
        }
        usb_set_intfdata(intf, NULL);

        intf->condition = USB_INTERFACE_UNBOUND;
        intf->needs_remote_wakeup = 0;

        /* Attempt to re-enable USB3 LPM, if the disable succeeded. */
        if (!lpm_disable_error)
                usb_unlocked_enable_lpm(udev);

        /* Unbound interfaces are always runtime-PM-disabled and -suspended */
        if (driver->supports_autosuspend)
                pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);

        /* Undo any residual pm_autopm_get_interface_* calls */
        for (r = atomic_read(&intf->pm_usage_cnt); r > 0; --r)
                usb_autopm_put_interface_no_suspend(intf);
        atomic_set(&intf->pm_usage_cnt, 0);

        if (!error)
                usb_autosuspend_device(udev);

        return 0;
}

/**
 * usb_driver_claim_interface - bind a driver to an interface
 * @driver: the driver to be bound
 * @iface: the interface to which it will be bound; must be in the
 *      usb device's active configuration
 * @priv: driver data associated with that interface
 *
 * This is used by usb device drivers that need to claim more than one
 * interface on a device when probing (audio and acm are current examples).
 * No device driver should directly modify internal usb_interface or
 * usb_device structure members.
 *
 * Few drivers should need to use this routine, since the most natural
 * way to bind to an interface is to return the private data from
 * the driver's probe() method.
 *
 * Callers must own the device lock, so driver probe() entries don't need
 * extra locking, but other call contexts may need to explicitly claim that
 * lock.
 *
 * Return: 0 on success.
 */
int usb_driver_claim_interface(struct usb_driver *driver,
                                struct usb_interface *iface, void *priv)
{
        struct device *dev = &iface->dev;
        struct usb_device *udev;
        int retval = 0;
        int lpm_disable_error;

        if (dev->driver)
                return -EBUSY;

        udev = interface_to_usbdev(iface);

        dev->driver = &driver->drvwrap.driver;
        usb_set_intfdata(iface, priv);
        iface->needs_binding = 0;

        iface->condition = USB_INTERFACE_BOUND;

        /* Disable LPM until this driver is bound. */
        lpm_disable_error = usb_unlocked_disable_lpm(udev);
        if (lpm_disable_error && driver->disable_hub_initiated_lpm) {
                dev_err(&iface->dev, "%s Failed to disable LPM for driver %s\n.",
                                __func__, driver->name);
                return -ENOMEM;
        }

        /* Claimed interfaces are initially inactive (suspended) and
         * runtime-PM-enabled, but only if the driver has autosuspend
         * support.  Otherwise they are marked active, to prevent the
         * device from being autosuspended, but left disabled.  In either
         * case they are sensitive to their children's power states.
         */
        pm_suspend_ignore_children(dev, false);
        if (driver->supports_autosuspend)
                pm_runtime_enable(dev);
        else
                pm_runtime_set_active(dev);

        /* if interface was already added, bind now; else let
         * the future device_add() bind it, bypassing probe()
         */
        if (device_is_registered(dev))
                retval = device_bind_driver(dev);

        /* Attempt to re-enable USB3 LPM, if the disable was successful. */
        if (!lpm_disable_error)
                usb_unlocked_enable_lpm(udev);

        return retval;
}
EXPORT_SYMBOL_GPL(usb_driver_claim_interface);

/**
 * usb_driver_release_interface - unbind a driver from an interface
 * @driver: the driver to be unbound
 * @iface: the interface from which it will be unbound
 *
 * This can be used by drivers to release an interface without waiting
 * for their disconnect() methods to be called.  In typical cases this
 * also causes the driver disconnect() method to be called.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 * Callers must own the device lock, so driver disconnect() entries don't
 * need extra locking, but other call contexts may need to explicitly claim
 * that lock.
 */
void usb_driver_release_interface(struct usb_driver *driver,
                                        struct usb_interface *iface)
{
        struct device *dev = &iface->dev;

        /* this should never happen, don't release something that's not ours */
        if (!dev->driver || dev->driver != &driver->drvwrap.driver)
                return;

        /* don't release from within disconnect() */
        if (iface->condition != USB_INTERFACE_BOUND)
                return;
        iface->condition = USB_INTERFACE_UNBINDING;

        /* Release via the driver core only if the interface
         * has already been registered
         */
        if (device_is_registered(dev)) {
                device_release_driver(dev);
        } else {
                device_lock(dev);
                usb_unbind_interface(dev);
                dev->driver = NULL;
                device_unlock(dev);
        }
}
EXPORT_SYMBOL_GPL(usb_driver_release_interface);

/* returns 0 if no match, 1 if match */
int usb_match_device(struct usb_device *dev, const struct usb_device_id *id)
{
        if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
            id->idVendor != le16_to_cpu(dev->descriptor.idVendor))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
            id->idProduct != le16_to_cpu(dev->descriptor.idProduct))
                return 0;

        /* No need to test id->bcdDevice_lo != 0, since 0 is never
           greater than any unsigned number. */
        if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
            (id->bcdDevice_lo > le16_to_cpu(dev->descriptor.bcdDevice)))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
            (id->bcdDevice_hi < le16_to_cpu(dev->descriptor.bcdDevice)))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
            (id->bDeviceClass != dev->descriptor.bDeviceClass))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
            (id->bDeviceSubClass != dev->descriptor.bDeviceSubClass))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
            (id->bDeviceProtocol != dev->descriptor.bDeviceProtocol))
                return 0;

        return 1;
}

/* returns 0 if no match, 1 if match */
int usb_match_one_id_intf(struct usb_device *dev,
                          struct usb_host_interface *intf,
                          const struct usb_device_id *id)
{
        /* The interface class, subclass, protocol and number should never be
         * checked for a match if the device class is Vendor Specific,
         * unless the match record specifies the Vendor ID. */
        if (dev->descriptor.bDeviceClass == USB_CLASS_VENDOR_SPEC &&
                        !(id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
                        (id->match_flags & (USB_DEVICE_ID_MATCH_INT_CLASS |
                                USB_DEVICE_ID_MATCH_INT_SUBCLASS |
                                USB_DEVICE_ID_MATCH_INT_PROTOCOL |
                                USB_DEVICE_ID_MATCH_INT_NUMBER)))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
            (id->bInterfaceClass != intf->desc.bInterfaceClass))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
            (id->bInterfaceSubClass != intf->desc.bInterfaceSubClass))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
            (id->bInterfaceProtocol != intf->desc.bInterfaceProtocol))
                return 0;

        if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER) &&
            (id->bInterfaceNumber != intf->desc.bInterfaceNumber))
                return 0;

        return 1;
}

/* returns 0 if no match, 1 if match */
int usb_match_one_id(struct usb_interface *interface,
                     const struct usb_device_id *id)
{
        struct usb_host_interface *intf;
        struct usb_device *dev;

        /* proc_connectinfo in devio.c may call us with id == NULL. */
        if (id == NULL)
                return 0;

        intf = interface->cur_altsetting;
        dev = interface_to_usbdev(interface);

        if (!usb_match_device(dev, id))
                return 0;

        return usb_match_one_id_intf(dev, intf, id);
}
EXPORT_SYMBOL_GPL(usb_match_one_id);

/**
 * usb_match_id - find first usb_device_id matching device or interface
 * @interface: the interface of interest
 * @id: array of usb_device_id structures, terminated by zero entry
 *
 * usb_match_id searches an array of usb_device_id's and returns
 * the first one matching the device or interface, or null.
 * This is used when binding (or rebinding) a driver to an interface.
 * Most USB device drivers will use this indirectly, through the usb core,
 * but some layered driver frameworks use it directly.
 * These device tables are exported with MODULE_DEVICE_TABLE, through
 * modutils, to support the driver loading functionality of USB hotplugging.
 *
 * Return: The first matching usb_device_id, or %NULL.
 *
 * What Matches:
 *
 * The "match_flags" element in a usb_device_id controls which
 * members are used.  If the corresponding bit is set, the
 * value in the device_id must match its corresponding member
 * in the device or interface descriptor, or else the device_id
 * does not match.
 *
 * "driver_info" is normally used only by device drivers,
 * but you can create a wildcard "matches anything" usb_device_id
 * as a driver's "modules.usbmap" entry if you provide an id with
 * only a nonzero "driver_info" field.  If you do this, the USB device
 * driver's probe() routine should use additional intelligence to
 * decide whether to bind to the specified interface.
 *
 * What Makes Good usb_device_id Tables:
 *
 * The match algorithm is very simple, so that intelligence in
 * driver selection must come from smart driver id records.
 * Unless you have good reasons to use another selection policy,
 * provide match elements only in related groups, and order match
 * specifiers from specific to general.  Use the macros provided
 * for that purpose if you can.
 *
 * The most specific match specifiers use device descriptor
 * data.  These are commonly used with product-specific matches;
 * the USB_DEVICE macro lets you provide vendor and product IDs,
 * and you can also match against ranges of product revisions.
 * These are widely used for devices with application or vendor
 * specific bDeviceClass values.
 *
 * Matches based on device class/subclass/protocol specifications
 * are slightly more general; use the USB_DEVICE_INFO macro, or
 * its siblings.  These are used with single-function devices
 * where bDeviceClass doesn't specify that each interface has
 * its own class.
 *
 * Matches based on interface class/subclass/protocol are the
 * most general; they let drivers bind to any interface on a
 * multiple-function device.  Use the USB_INTERFACE_INFO
 * macro, or its siblings, to match class-per-interface style
 * devices (as recorded in bInterfaceClass).
 *
 * Note that an entry created by USB_INTERFACE_INFO won't match
 * any interface if the device class is set to Vendor-Specific.
 * This is deliberate; according to the USB spec the meanings of
 * the interface class/subclass/protocol for these devices are also
 * vendor-specific, and hence matching against a standard product
 * class wouldn't work anyway.  If you really want to use an
 * interface-based match for such a device, create a match record
 * that also specifies the vendor ID.  (Unforunately there isn't a
 * standard macro for creating records like this.)
 *
 * Within those groups, remember that not all combinations are
 * meaningful.  For example, don't give a product version range
 * without vendor and product IDs; or specify a protocol without
 * its associated class and subclass.
 */
const struct usb_device_id *usb_match_id(struct usb_interface *interface,
                                         const struct usb_device_id *id)
{
        /* proc_connectinfo in devio.c may call us with id == NULL. */
        if (id == NULL)
                return NULL;

        /* It is important to check that id->driver_info is nonzero,
           since an entry that is all zeroes except for a nonzero
           id->driver_info is the way to create an entry that
           indicates that the driver want to examine every
           device and interface. */
        for (; id->idVendor || id->idProduct || id->bDeviceClass ||
               id->bInterfaceClass || id->driver_info; id++) {
                if (usb_match_one_id(interface, id))
                        return id;
        }

        return NULL;
}
EXPORT_SYMBOL_GPL(usb_match_id);

static int usb_device_match(struct device *dev, struct device_driver *drv)
{
        /* devices and interfaces are handled separately */
        if (is_usb_device(dev)) {

                /* interface drivers never match devices */
                if (!is_usb_device_driver(drv))
                        return 0;

                /* TODO: Add real matching code */
                return 1;

        } else if (is_usb_interface(dev)) {
                struct usb_interface *intf;
                struct usb_driver *usb_drv;
                const struct usb_device_id *id;

                /* device drivers never match interfaces */
                if (is_usb_device_driver(drv))
                        return 0;

                intf = to_usb_interface(dev);
                usb_drv = to_usb_driver(drv);

                id = usb_match_id(intf, usb_drv->id_table);
                if (id)
                        return 1;

                id = usb_match_dynamic_id(intf, usb_drv);
                if (id)
                        return 1;
        }

        return 0;
}

static int usb_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct usb_device *usb_dev;

        if (is_usb_device(dev)) {
                usb_dev = to_usb_device(dev);
        } else if (is_usb_interface(dev)) {
                struct usb_interface *intf = to_usb_interface(dev);

                usb_dev = interface_to_usbdev(intf);
        } else {
                return 0;
        }

        if (usb_dev->devnum < 0) {
                /* driver is often null here; dev_dbg() would oops */
                pr_debug("usb %s: already deleted?\n", dev_name(dev));
                return -ENODEV;
        }
        if (!usb_dev->bus) {
                pr_debug("usb %s: bus removed?\n", dev_name(dev));
                return -ENODEV;
        }

        /* per-device configurations are common */
        if (add_uevent_var(env, "PRODUCT=%x/%x/%x",
                           le16_to_cpu(usb_dev->descriptor.idVendor),
                           le16_to_cpu(usb_dev->descriptor.idProduct),
                           le16_to_cpu(usb_dev->descriptor.bcdDevice)))
                return -ENOMEM;

        /* class-based driver binding models */
        if (add_uevent_var(env, "TYPE=%d/%d/%d",
                           usb_dev->descriptor.bDeviceClass,
                           usb_dev->descriptor.bDeviceSubClass,
                           usb_dev->descriptor.bDeviceProtocol))
                return -ENOMEM;

        return 0;
}

/**
 * usb_register_device_driver - register a USB device (not interface) driver
 * @new_udriver: USB operations for the device driver
 * @owner: module owner of this driver.
 *
 * Registers a USB device driver with the USB core.  The list of
 * unattached devices will be rescanned whenever a new driver is
 * added, allowing the new driver to attach to any recognized devices.
 *
 * Return: A negative error code on failure and 0 on success.
 */
int usb_register_device_driver(struct usb_device_driver *new_udriver,
                struct module *owner)
{
        int retval = 0;

        if (usb_disabled())
                return -ENODEV;

        new_udriver->drvwrap.for_devices = 1;
        new_udriver->drvwrap.driver.name = (char *) new_udriver->name;
        new_udriver->drvwrap.driver.bus = &usb_bus_type;
        new_udriver->drvwrap.driver.probe = usb_probe_device;
        new_udriver->drvwrap.driver.remove = usb_unbind_device;
        new_udriver->drvwrap.driver.owner = owner;

        retval = driver_register(&new_udriver->drvwrap.driver);

        if (!retval)
                pr_info("%s: registered new device driver %s\n",
                        usbcore_name, new_udriver->name);
        else
                printk(KERN_ERR "%s: error %d registering device "
                        "       driver %s\n",
                        usbcore_name, retval, new_udriver->name);

        return retval;
}
EXPORT_SYMBOL_GPL(usb_register_device_driver);

/**
 * usb_deregister_device_driver - unregister a USB device (not interface) driver
 * @udriver: USB operations of the device driver to unregister
 * Context: must be able to sleep
 *
 * Unlinks the specified driver from the internal USB driver list.
 */
void usb_deregister_device_driver(struct usb_device_driver *udriver)
{
        pr_info("%s: deregistering device driver %s\n",
                        usbcore_name, udriver->name);

        driver_unregister(&udriver->drvwrap.driver);
}
EXPORT_SYMBOL_GPL(usb_deregister_device_driver);

/**
 * usb_register_driver - register a USB interface driver
 * @new_driver: USB operations for the interface driver
 * @owner: module owner of this driver.
 * @mod_name: module name string
 *
 * Registers a USB interface driver with the USB core.  The list of
 * unattached interfaces will be rescanned whenever a new driver is
 * added, allowing the new driver to attach to any recognized interfaces.
 *
 * Return: A negative error code on failure and 0 on success.
 *
 * NOTE: if you want your driver to use the USB major number, you must call
 * usb_register_dev() to enable that functionality.  This function no longer
 * takes care of that.
 */
int usb_register_driver(struct usb_driver *new_driver, struct module *owner,
                        const char *mod_name)
{
        int retval = 0;

        if (usb_disabled())
                return -ENODEV;

        new_driver->drvwrap.for_devices = 0;
        new_driver->drvwrap.driver.name = (char *) new_driver->name;
        new_driver->drvwrap.driver.bus = &usb_bus_type;
        new_driver->drvwrap.driver.probe = usb_probe_interface;
        new_driver->drvwrap.driver.remove = usb_unbind_interface;
        new_driver->drvwrap.driver.owner = owner;
        new_driver->drvwrap.driver.mod_name = mod_name;
        spin_lock_init(&new_driver->dynids.lock);
        INIT_LIST_HEAD(&new_driver->dynids.list);

        retval = driver_register(&new_driver->drvwrap.driver);
        if (retval)
                goto out;

        retval = usb_create_newid_files(new_driver);
        if (retval)
                goto out_newid;

        pr_info("%s: registered new interface driver %s\n",
                        usbcore_name, new_driver->name);

out:
        return retval;

out_newid:
        driver_unregister(&new_driver->drvwrap.driver);

        printk(KERN_ERR "%s: error %d registering interface "
                        "       driver %s\n",
                        usbcore_name, retval, new_driver->name);
        goto out;
}
EXPORT_SYMBOL_GPL(usb_register_driver);

/**
 * usb_deregister - unregister a USB interface driver
 * @driver: USB operations of the interface driver to unregister
 * Context: must be able to sleep
 *
 * Unlinks the specified driver from the internal USB driver list.
 *
 * NOTE: If you called usb_register_dev(), you still need to call
 * usb_deregister_dev() to clean up your driver's allocated minor numbers,
 * this * call will no longer do it for you.
 */
void usb_deregister(struct usb_driver *driver)
{
        pr_info("%s: deregistering interface driver %s\n",
                        usbcore_name, driver->name);

        usb_remove_newid_files(driver);
        driver_unregister(&driver->drvwrap.driver);
        usb_free_dynids(driver);
}
EXPORT_SYMBOL_GPL(usb_deregister);

/* Forced unbinding of a USB interface driver, either because
 * it doesn't support pre_reset/post_reset/reset_resume or
 * because it doesn't support suspend/resume.
 *
 * The caller must hold @intf's device's lock, but not @intf's lock.
 */
void usb_forced_unbind_intf(struct usb_interface *intf)
{
        struct usb_driver *driver = to_usb_driver(intf->dev.driver);

        dev_dbg(&intf->dev, "forced unbind\n");
        usb_driver_release_interface(driver, intf);

        /* Mark the interface for later rebinding */
        intf->needs_binding = 1;
}

/*
 * Unbind drivers for @udev's marked interfaces.  These interfaces have
 * the needs_binding flag set, for example by usb_resume_interface().
 *
 * The caller must hold @udev's device lock.
 */
static void unbind_marked_interfaces(struct usb_device *udev)
{
        struct usb_host_config  *config;
        int                     i;
        struct usb_interface    *intf;

        config = udev->actconfig;
        if (config) {
                for (i = 0; i < config->desc.bNumInterfaces; ++i) {
                        intf = config->interface[i];
                        if (intf->dev.driver && intf->needs_binding)
                                usb_forced_unbind_intf(intf);
                }
        }
}

/* Delayed forced unbinding of a USB interface driver and scan
 * for rebinding.
 *
 * The caller must hold @intf's device's lock, but not @intf's lock.
 *
 * Note: Rebinds will be skipped if a system sleep transition is in
 * progress and the PM "complete" callback hasn't occurred yet.
 */
static void usb_rebind_intf(struct usb_interface *intf)
{
        int rc;

        /* Delayed unbind of an existing driver */
        if (intf->dev.driver)
                usb_forced_unbind_intf(intf);

        /* Try to rebind the interface */
        if (!intf->dev.power.is_prepared) {
                intf->needs_binding = 0;
                rc = device_attach(&intf->dev);
                if (rc < 0)
                        dev_warn(&intf->dev, "rebind failed: %d\n", rc);
        }
}

/*
 * Rebind drivers to @udev's marked interfaces.  These interfaces have
 * the needs_binding flag set.
 *
 * The caller must hold @udev's device lock.
 */
static void rebind_marked_interfaces(struct usb_device *udev)
{
        struct usb_host_config  *config;
        int                     i;
        struct usb_interface    *intf;

        config = udev->actconfig;
        if (config) {
                for (i = 0; i < config->desc.bNumInterfaces; ++i) {
                        intf = config->interface[i];
                        if (intf->needs_binding)
                                usb_rebind_intf(intf);
                }
        }
}

/*
 * Unbind all of @udev's marked interfaces and then rebind all of them.
 * This ordering is necessary because some drivers claim several interfaces
 * when they are first probed.
 *
 * The caller must hold @udev's device lock.
 */
void usb_unbind_and_rebind_marked_interfaces(struct usb_device *udev)
{
        unbind_marked_interfaces(udev);
        rebind_marked_interfaces(udev);
}

#ifdef CONFIG_PM

/* Unbind drivers for @udev's interfaces that don't support suspend/resume
 * There is no check for reset_resume here because it can be determined
 * only during resume whether reset_resume is needed.
 *
 * The caller must hold @udev's device lock.
 */
static void unbind_no_pm_drivers_interfaces(struct usb_device *udev)
{
        struct usb_host_config  *config;
        int                     i;
        struct usb_interface    *intf;
        struct usb_driver       *drv;

        config = udev->actconfig;
        if (config) {
                for (i = 0; i < config->desc.bNumInterfaces; ++i) {
                        intf = config->interface[i];

                        if (intf->dev.driver) {
                                drv = to_usb_driver(intf->dev.driver);
                                if (!drv->suspend || !drv->resume)
                                        usb_forced_unbind_intf(intf);
                        }
                }
        }
}

static int usb_suspend_device(struct usb_device *udev, pm_message_t msg)
{
        struct usb_device_driver        *udriver;
        int                             status = 0;

        if (udev->state == USB_STATE_NOTATTACHED ||
                        udev->state == USB_STATE_SUSPENDED)
                goto done;

        /* For devices that don't have a driver, we do a generic suspend. */
        if (udev->dev.driver)
                udriver = to_usb_device_driver(udev->dev.driver);
        else {
                udev->do_remote_wakeup = 0;
                udriver = &usb_generic_driver;
        }
        status = udriver->suspend(udev, msg);

 done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
        return status;
}

static int usb_resume_device(struct usb_device *udev, pm_message_t msg)
{
        struct usb_device_driver        *udriver;
        int                             status = 0;

        if (udev->state == USB_STATE_NOTATTACHED)
                goto done;

        /* Can't resume it if it doesn't have a driver. */
        if (udev->dev.driver == NULL) {
                status = -ENOTCONN;
                goto done;
        }

        /* Non-root devices on a full/low-speed bus must wait for their
         * companion high-speed root hub, in case a handoff is needed.
         */
        if (!PMSG_IS_AUTO(msg) && udev->parent && udev->bus->hs_companion)
                device_pm_wait_for_dev(&udev->dev,
                                &udev->bus->hs_companion->root_hub->dev);

        if (udev->quirks & USB_QUIRK_RESET_RESUME)
                udev->reset_resume = 1;

        udriver = to_usb_device_driver(udev->dev.driver);
        status = udriver->resume(udev, msg);

 done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
        return status;
}

static int usb_suspend_interface(struct usb_device *udev,
                struct usb_interface *intf, pm_message_t msg)
{
        struct usb_driver       *driver;
        int                     status = 0;

        if (udev->state == USB_STATE_NOTATTACHED ||
                        intf->condition == USB_INTERFACE_UNBOUND)
                goto done;
        driver = to_usb_driver(intf->dev.driver);

        /* at this time we know the driver supports suspend */
        status = driver->suspend(intf, msg);
        if (status && !PMSG_IS_AUTO(msg))
                dev_err(&intf->dev, "suspend error %d\n", status);

 done:
        dev_vdbg(&intf->dev, "%s: status %d\n", __func__, status);
        return status;
}

static int usb_resume_interface(struct usb_device *udev,
                struct usb_interface *intf, pm_message_t msg, int reset_resume)
{
        struct usb_driver       *driver;
        int                     status = 0;

        if (udev->state == USB_STATE_NOTATTACHED)
                goto done;

        /* Don't let autoresume interfere with unbinding */
        if (intf->condition == USB_INTERFACE_UNBINDING)
                goto done;

        /* Can't resume it if it doesn't have a driver. */
        if (intf->condition == USB_INTERFACE_UNBOUND) {

                /* Carry out a deferred switch to altsetting 0 */
                if (intf->needs_altsetting0 && !intf->dev.power.is_prepared) {
                        usb_set_interface(udev, intf->altsetting[0].
                                        desc.bInterfaceNumber, 0);
                        intf->needs_altsetting0 = 0;
                }
                goto done;
        }

        /* Don't resume if the interface is marked for rebinding */
        if (intf->needs_binding)
                goto done;
        driver = to_usb_driver(intf->dev.driver);

        if (reset_resume) {
                if (driver->reset_resume) {
                        status = driver->reset_resume(intf);
                        if (status)
                                dev_err(&intf->dev, "%s error %d\n",
                                                "reset_resume", status);
                } else {
                        intf->needs_binding = 1;
                        dev_warn(&intf->dev, "no %s for driver %s?\n",
                                        "reset_resume", driver->name);
                }
        } else {
                status = driver->resume(intf);
                if (status)
                        dev_err(&intf->dev, "resume error %d\n", status);
        }

done:
        dev_vdbg(&intf->dev, "%s: status %d\n", __func__, status);

        /* Later we will unbind the driver and/or reprobe, if necessary */
        return status;
}

/**
 * usb_suspend_both - suspend a USB device and its interfaces
 * @udev: the usb_device to suspend
 * @msg: Power Management message describing this state transition
 *
 * This is the central routine for suspending USB devices.  It calls the
 * suspend methods for all the interface drivers in @udev and then calls
 * the suspend method for @udev itself.  When the routine is called in
 * autosuspend, if an error occurs at any stage, all the interfaces
 * which were suspended are resumed so that they remain in the same
 * state as the device, but when called from system sleep, all error
 * from suspend methods of interfaces and the non-root-hub device itself
 * are simply ignored, so all suspended interfaces are only resumed
 * to the device's state when @udev is root-hub and its suspend method
 * returns failure.
 *
 * Autosuspend requests originating from a child device or an interface
 * driver may be made without the protection of @udev's device lock, but
 * all other suspend calls will hold the lock.  Usbcore will insure that
 * method calls do not arrive during bind, unbind, or reset operations.
 * However drivers must be prepared to handle suspend calls arriving at
 * unpredictable times.
 *
 * This routine can run only in process context.
 *
 * Return: 0 if the suspend succeeded.
 */
static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
{
        int                     status = 0;
        int                     i = 0, n = 0;
        struct usb_interface    *intf;

        if (udev->state == USB_STATE_NOTATTACHED ||
                        udev->state == USB_STATE_SUSPENDED)
                goto done;

        /* Suspend all the interfaces and then udev itself */
        if (udev->actconfig) {
                n = udev->actconfig->desc.bNumInterfaces;
                for (i = n - 1; i >= 0; --i) {
                        intf = udev->actconfig->interface[i];
                        status = usb_suspend_interface(udev, intf, msg);

                        /* Ignore errors during system sleep transitions */
                        if (!PMSG_IS_AUTO(msg))
                                status = 0;
                        if (status != 0)
                                break;
                }
        }
        if (status == 0) {
                status = usb_suspend_device(udev, msg);

                /*
                 * Ignore errors from non-root-hub devices during
                 * system sleep transitions.  For the most part,
                 * these devices should go to low power anyway when
                 * the entire bus is suspended.
                 */
                if (udev->parent && !PMSG_IS_AUTO(msg))
                        status = 0;
        }

        /* If the suspend failed, resume interfaces that did get suspended */
        if (status != 0) {
                if (udev->actconfig) {
                        msg.event ^= (PM_EVENT_SUSPEND | PM_EVENT_RESUME);
                        while (++i < n) {
                                intf = udev->actconfig->interface[i];
                                usb_resume_interface(udev, intf, msg, 0);
                        }
                }

        /* If the suspend succeeded then prevent any more URB submissions
         * and flush any outstanding URBs.
         */
        } else {
                udev->can_submit = 0;
                for (i = 0; i < 16; ++i) {
                        usb_hcd_flush_endpoint(udev, udev->ep_out[i]);
                        usb_hcd_flush_endpoint(udev, udev->ep_in[i]);
                }
        }

 done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
        return status;
}

/**
 * usb_resume_both - resume a USB device and its interfaces
 * @udev: the usb_device to resume
 * @msg: Power Management message describing this state transition
 *
 * This is the central routine for resuming USB devices.  It calls the
 * the resume method for @udev and then calls the resume methods for all
 * the interface drivers in @udev.
 *
 * Autoresume requests originating from a child device or an interface
 * driver may be made without the protection of @udev's device lock, but
 * all other resume calls will hold the lock.  Usbcore will insure that
 * method calls do not arrive during bind, unbind, or reset operations.
 * However drivers must be prepared to handle resume calls arriving at
 * unpredictable times.
 *
 * This routine can run only in process context.
 *
 * Return: 0 on success.
 */
static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
{
        int                     status = 0;
        int                     i;
        struct usb_interface    *intf;

        if (udev->state == USB_STATE_NOTATTACHED) {
                status = -ENODEV;
                goto done;
        }
        udev->can_submit = 1;

        /* Resume the device */
        if (udev->state == USB_STATE_SUSPENDED || udev->reset_resume)
                status = usb_resume_device(udev, msg);

        /* Resume the interfaces */
        if (status == 0 && udev->actconfig) {
                for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
                        intf = udev->actconfig->interface[i];
                        usb_resume_interface(udev, intf, msg,
                                        udev->reset_resume);
                }
        }
        usb_mark_last_busy(udev);

 done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
        if (!status)
                udev->reset_resume = 0;
        return status;
}

static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
{
        int     w;

        /* Remote wakeup is needed only when we actually go to sleep.
         * For things like FREEZE and QUIESCE, if the device is already
         * autosuspended then its current wakeup setting is okay.
         */
        if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_QUIESCE) {
                if (udev->state != USB_STATE_SUSPENDED)
                        udev->do_remote_wakeup = 0;
                return;
        }

        /* Enable remote wakeup if it is allowed, even if no interface drivers
         * actually want it.
         */
        w = device_may_wakeup(&udev->dev);

        /* If the device is autosuspended with the wrong wakeup setting,
         * autoresume now so the setting can be changed.
         */
        if (udev->state == USB_STATE_SUSPENDED && w != udev->do_remote_wakeup)
                pm_runtime_resume(&udev->dev);
        udev->do_remote_wakeup = w;
}

/* The device lock is held by the PM core */
int usb_suspend(struct device *dev, pm_message_t msg)
{
        struct usb_device       *udev = to_usb_device(dev);

        unbind_no_pm_drivers_interfaces(udev);

        /* From now on we are sure all drivers support suspend/resume
         * but not necessarily reset_resume()
         * so we may still need to unbind and rebind upon resume
         */
        choose_wakeup(udev, msg);
        return usb_suspend_both(udev, msg);
}

/* The device lock is held by the PM core */
int usb_resume_complete(struct device *dev)
{
        struct usb_device *udev = to_usb_device(dev);

        /* For PM complete calls, all we do is rebind interfaces
         * whose needs_binding flag is set
         */
        if (udev->state != USB_STATE_NOTATTACHED)
                rebind_marked_interfaces(udev);
        return 0;
}

/* The device lock is held by the PM core */
int usb_resume(struct device *dev, pm_message_t msg)
{
        struct usb_device       *udev = to_usb_device(dev);
        int                     status;

        /* For all calls, take the device back to full power and
         * tell the PM core in case it was autosuspended previously.
         * Unbind the interfaces that will need rebinding later,
         * because they fail to support reset_resume.
         * (This can't be done in usb_resume_interface()
         * above because it doesn't own the right set of locks.)
         */
        status = usb_resume_both(udev, msg);
        if (status == 0) {
                pm_runtime_disable(dev);
                pm_runtime_set_active(dev);
                pm_runtime_enable(dev);
                unbind_marked_interfaces(udev);
        }

        /* Avoid PM error messages for devices disconnected while suspended
         * as we'll display regular disconnect messages just a bit later.
         */
        if (status == -ENODEV || status == -ESHUTDOWN)
                status = 0;
        return status;
}

#endif /* CONFIG_PM */

#ifdef CONFIG_PM_RUNTIME

/**
 * usb_enable_autosuspend - allow a USB device to be autosuspended
 * @udev: the USB device which may be autosuspended
 *
 * This routine allows @udev to be autosuspended.  An autosuspend won't
 * take place until the autosuspend_delay has elapsed and all the other
 * necessary conditions are satisfied.
 *
 * The caller must hold @udev's device lock.
 */
void usb_enable_autosuspend(struct usb_device *udev)
{
        pm_runtime_allow(&udev->dev);
}
EXPORT_SYMBOL_GPL(usb_enable_autosuspend);

/**
 * usb_disable_autosuspend - prevent a USB device from being autosuspended
 * @udev: the USB device which may not be autosuspended
 *
 * This routine prevents @udev from being autosuspended and wakes it up
 * if it is already autosuspended.
 *
 * The caller must hold @udev's device lock.
 */
void usb_disable_autosuspend(struct usb_device *udev)
{
        pm_runtime_forbid(&udev->dev);
}
EXPORT_SYMBOL_GPL(usb_disable_autosuspend);

/**
 * usb_autosuspend_device - delayed autosuspend of a USB device and its interfaces
 * @udev: the usb_device to autosuspend
 *
 * This routine should be called when a core subsystem is finished using
 * @udev and wants to allow it to autosuspend.  Examples would be when
 * @udev's device file in usbfs is closed or after a configuration change.
 *
 * @udev's usage counter is decremented; if it drops to 0 and all the
 * interfaces are inactive then a delayed autosuspend will be attempted.
 * The attempt may fail (see autosuspend_check()).
 *
 * The caller must hold @udev's device lock.
 *
 * This routine can run only in process context.
 */
void usb_autosuspend_device(struct usb_device *udev)
{
        int     status;

        usb_mark_last_busy(udev);
        status = pm_runtime_put_sync_autosuspend(&udev->dev);
        dev_vdbg(&udev->dev, "%s: cnt %d -> %d\n",
                        __func__, atomic_read(&udev->dev.power.usage_count),
                        status);
}

/**
 * usb_autoresume_device - immediately autoresume a USB device and its interfaces
 * @udev: the usb_device to autoresume
 *
 * This routine should be called when a core subsystem wants to use @udev
 * and needs to guarantee that it is not suspended.  No autosuspend will
 * occur until usb_autosuspend_device() is called.  (Note that this will
 * not prevent suspend events originating in the PM core.)  Examples would
 * be when @udev's device file in usbfs is opened or when a remote-wakeup
 * request is received.
 *
 * @udev's usage counter is incremented to prevent subsequent autosuspends.
 * However if the autoresume fails then the usage counter is re-decremented.
 *
 * The caller must hold @udev's device lock.
 *
 * This routine can run only in process context.
 *
 * Return: 0 on success. A negative error code otherwise.
 */
int usb_autoresume_device(struct usb_device *udev)
{
        int     status;

        status = pm_runtime_get_sync(&udev->dev);
        if (status < 0)
                pm_runtime_put_sync(&udev->dev);
        dev_vdbg(&udev->dev, "%s: cnt %d -> %d\n",
                        __func__, atomic_read(&udev->dev.power.usage_count),
                        status);
        if (status > 0)
                status = 0;
        return status;
}

/**
 * usb_autopm_put_interface - decrement a USB interface's PM-usage counter
 * @intf: the usb_interface whose counter should be decremented
 *
 * This routine should be called by an interface driver when it is
 * finished using @intf and wants to allow it to autosuspend.  A typical
 * example would be a character-device driver when its device file is
 * closed.
 *
 * The routine decrements @intf's usage counter.  When the counter reaches
 * 0, a delayed autosuspend request for @intf's device is attempted.  The
 * attempt may fail (see autosuspend_check()).
 *
 * This routine can run only in process context.
 */
void usb_autopm_put_interface(struct usb_interface *intf)
{
        struct usb_device       *udev = interface_to_usbdev(intf);
        int                     status;

        usb_mark_last_busy(udev);
        atomic_dec(&intf->pm_usage_cnt);
        status = pm_runtime_put_sync(&intf->dev);
        dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                        __func__, atomic_read(&intf->dev.power.usage_count),
                        status);
}
EXPORT_SYMBOL_GPL(usb_autopm_put_interface);

/**
 * usb_autopm_put_interface_async - decrement a USB interface's PM-usage counter
 * @intf: the usb_interface whose counter should be decremented
 *
 * This routine does much the same thing as usb_autopm_put_interface():
 * It decrements @intf's usage counter and schedules a delayed
 * autosuspend request if the counter is <= 0.  The difference is that it
 * does not perform any synchronization; callers should hold a private
 * lock and handle all synchronization issues themselves.
 *
 * Typically a driver would call this routine during an URB's completion
 * handler, if no more URBs were pending.
 *
 * This routine can run in atomic context.
 */
void usb_autopm_put_interface_async(struct usb_interface *intf)
{
        struct usb_device       *udev = interface_to_usbdev(intf);
        int                     status;

        usb_mark_last_busy(udev);
        atomic_dec(&intf->pm_usage_cnt);
        status = pm_runtime_put(&intf->dev);
        dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                        __func__, atomic_read(&intf->dev.power.usage_count),
                        status);
}
EXPORT_SYMBOL_GPL(usb_autopm_put_interface_async);

/**
 * usb_autopm_put_interface_no_suspend - decrement a USB interface's PM-usage counter
 * @intf: the usb_interface whose counter should be decremented
 *
 * This routine decrements @intf's usage counter but does not carry out an
 * autosuspend.
 *
 * This routine can run in atomic context.
 */
void usb_autopm_put_interface_no_suspend(struct usb_interface *intf)
{
        struct usb_device       *udev = interface_to_usbdev(intf);

        usb_mark_last_busy(udev);
        atomic_dec(&intf->pm_usage_cnt);
        pm_runtime_put_noidle(&intf->dev);
}
EXPORT_SYMBOL_GPL(usb_autopm_put_interface_no_suspend);

/**
 * usb_autopm_get_interface - increment a USB interface's PM-usage counter
 * @intf: the usb_interface whose counter should be incremented
 *
 * This routine should be called by an interface driver when it wants to
 * use @intf and needs to guarantee that it is not suspended.  In addition,
 * the routine prevents @intf from being autosuspended subsequently.  (Note
 * that this will not prevent suspend events originating in the PM core.)
 * This prevention will persist until usb_autopm_put_interface() is called
 * or @intf is unbound.  A typical example would be a character-device
 * driver when its device file is opened.
 *
 * @intf's usage counter is incremented to prevent subsequent autosuspends.
 * However if the autoresume fails then the counter is re-decremented.
 *
 * This routine can run only in process context.
 *
 * Return: 0 on success.
 */
int usb_autopm_get_interface(struct usb_interface *intf)
{
        int     status;

        status = pm_runtime_get_sync(&intf->dev);
        if (status < 0)
                pm_runtime_put_sync(&intf->dev);
        else
                atomic_inc(&intf->pm_usage_cnt);
        dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                        __func__, atomic_read(&intf->dev.power.usage_count),
                        status);
        if (status > 0)
                status = 0;
        return status;
}
EXPORT_SYMBOL_GPL(usb_autopm_get_interface);

/**
 * usb_autopm_get_interface_async - increment a USB interface's PM-usage counter
 * @intf: the usb_interface whose counter should be incremented
 *
 * This routine does much the same thing as
 * usb_autopm_get_interface(): It increments @intf's usage counter and
 * queues an autoresume request if the device is suspended.  The
 * differences are that it does not perform any synchronization (callers
 * should hold a private lock and handle all synchronization issues
 * themselves), and it does not autoresume the device directly (it only
 * queues a request).  After a successful call, the device may not yet be
 * resumed.
 *
 * This routine can run in atomic context.
 *
 * Return: 0 on success. A negative error code otherwise.
 */
int usb_autopm_get_interface_async(struct usb_interface *intf)
{
        int     status;

        status = pm_runtime_get(&intf->dev);
        if (status < 0 && status != -EINPROGRESS)
                pm_runtime_put_noidle(&intf->dev);
        else
                atomic_inc(&intf->pm_usage_cnt);
        dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                        __func__, atomic_read(&intf->dev.power.usage_count),
                        status);
        if (status > 0 || status == -EINPROGRESS)
                status = 0;
        return status;
}
EXPORT_SYMBOL_GPL(usb_autopm_get_interface_async);

/**
 * usb_autopm_get_interface_no_resume - increment a USB interface's PM-usage counter
 * @intf: the usb_interface whose counter should be incremented
 *
 * This routine increments @intf's usage counter but does not carry out an
 * autoresume.
 *
 * This routine can run in atomic context.
 */
void usb_autopm_get_interface_no_resume(struct usb_interface *intf)
{
        struct usb_device       *udev = interface_to_usbdev(intf);

        usb_mark_last_busy(udev);
        atomic_inc(&intf->pm_usage_cnt);
        pm_runtime_get_noresume(&intf->dev);
}
EXPORT_SYMBOL_GPL(usb_autopm_get_interface_no_resume);

/* Internal routine to check whether we may autosuspend a device. */
static int autosuspend_check(struct usb_device *udev)
{
        int                     w, i;
        struct usb_interface    *intf;

        /* Fail if autosuspend is disabled, or any interfaces are in use, or
         * any interface drivers require remote wakeup but it isn't available.
         */
        w = 0;
        if (udev->actconfig) {
                for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
                        intf = udev->actconfig->interface[i];

                        /* We don't need to check interfaces that are
                         * disabled for runtime PM.  Either they are unbound
                         * or else their drivers don't support autosuspend
                         * and so they are permanently active.
                         */
                        if (intf->dev.power.disable_depth)
                                continue;
                        if (atomic_read(&intf->dev.power.usage_count) > 0)
                                return -EBUSY;
                        w |= intf->needs_remote_wakeup;

                        /* Don't allow autosuspend if the device will need
                         * a reset-resume and any of its interface drivers
                         * doesn't include support or needs remote wakeup.
                         */
                        if (udev->quirks & USB_QUIRK_RESET_RESUME) {
                                struct usb_driver *driver;

                                driver = to_usb_driver(intf->dev.driver);
                                if (!driver->reset_resume ||
                                                intf->needs_remote_wakeup)
                                        return -EOPNOTSUPP;
                        }
                }
        }
        if (w && !device_can_wakeup(&udev->dev)) {
                dev_dbg(&udev->dev, "remote wakeup needed for autosuspend\n");
                return -EOPNOTSUPP;
        }
        udev->do_remote_wakeup = w;
        return 0;
}

int usb_runtime_suspend(struct device *dev)
{
        struct usb_device       *udev = to_usb_device(dev);
        int                     status;

        /* A USB device can be suspended if it passes the various autosuspend
         * checks.  Runtime suspend for a USB device means suspending all the
         * interfaces and then the device itself.
         */
        if (autosuspend_check(udev) != 0)
                return -EAGAIN;

        status = usb_suspend_both(udev, PMSG_AUTO_SUSPEND);

        /* Allow a retry if autosuspend failed temporarily */
        if (status == -EAGAIN || status == -EBUSY)
                usb_mark_last_busy(udev);

        /*
         * The PM core reacts badly unless the return code is 0,
         * -EAGAIN, or -EBUSY, so always return -EBUSY on an error
         * (except for root hubs, because they don't suspend through
         * an upstream port like other USB devices).
         */
        if (status != 0 && udev->parent)
                return -EBUSY;
        return status;
}

int usb_runtime_resume(struct device *dev)
{
        struct usb_device       *udev = to_usb_device(dev);
        int                     status;

        /* Runtime resume for a USB device means resuming both the device
         * and all its interfaces.
         */
        status = usb_resume_both(udev, PMSG_AUTO_RESUME);
        return status;
}

int usb_runtime_idle(struct device *dev)
{
        struct usb_device       *udev = to_usb_device(dev);

        /* An idle USB device can be suspended if it passes the various
         * autosuspend checks.
         */
        if (autosuspend_check(udev) == 0)
                pm_runtime_autosuspend(dev);
        /* Tell the core not to suspend it, though. */
        return -EBUSY;
}

int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);
        int ret = -EPERM;

        if (enable && !udev->usb2_hw_lpm_allowed)
                return 0;

        if (hcd->driver->set_usb2_hw_lpm) {
                ret = hcd->driver->set_usb2_hw_lpm(hcd, udev, enable);
                if (!ret)
                        udev->usb2_hw_lpm_enabled = enable;
        }

        return ret;
}

#endif /* CONFIG_PM_RUNTIME */

struct bus_type usb_bus_type = {
        .name =         "usb",
        .match =        usb_device_match,
        .uevent =       usb_uevent,
};